1. Technical Field
The present invention relates to a light emitting device, an electronic apparatus, and a driving method of a light emitting device.
2. Related Art
In recent years, various light emitting devices each using a light-emitting element such as an Organic Light Emitting Diode (hereinafter referred to as an “OLED”) element which is called an organic EL (Electro Luminescent) element, a light-emitting polymer element, or the like have been proposed.
For example, in JP-A-2006-58893, a light emitting device is disclosed which selectively allows only one of either a main panel (a front display) or a sub-panel (a back display) to emit light. The light emitting device disclosed in JP-A-2006-58893 includes a main scanning drive section which sequentially supplies a selection signal to a plurality of scanning lines of the main panel, a sub-scanning drive section which sequentially supplies a selection signal to a plurality of scanning lines of the sub-panel, a data driving section which supplies data voltage corresponding to an image signal to a plurality of data lines which is shared by the main panel and the sub-panel, and a driving control section which controls an operation of the light emitting device. The driving control section controls so as to allow only one of either the main scanning drive section or the sub-scanning drive section to operate while allowing the data driving section to operate.
In the light emitting device disclosed in JP-A-2006-58893, the configuration of a pixel circuit in the main panel and the configuration of a pixel circuit in the sub-panel are the same as each other and take the configuration of FIG. 18. As shown in FIG. 18, a pixel circuit is configured to include a P-channel type driving transistor DM, a light-emitting element OLED, a P-channel type switching transistor SM, and a capacitor Cst. The driving transistor DM and the light-emitting element OLED are connected in series to each other between a high potential side electric supply line, to which a high potential side power supply potential VDD is supplied, and a low potential side electric supply line, to which a low potential side power supply potential VSS is supplied. Each of the high potential side electric supply line and the low potential side electric supply line is connected in common to each pixel circuit of the main panel and the sub-panel. The capacitor Cst is provided between the gate and the source of the driving transistor DM. The switching transistor SM is provided between the gate of the driving transistor DM and a data line D and the gate thereof is connected to a scanning line S. The on/off state of the switching transistor SM is controlled in accordance with a selection signal which is output to the scanning line S.
Now, a case where while the main panel is made to emit light, the sub-panel is made to not emit light is assumed. In this case, since the selection signal is not output to the scanning line S corresponding to the pixel circuit of the sub-panel, the switching transistor SM of the pixel circuit of the sub-panel is maintained in an OFF state. Therefore, a data voltage which is output to the data line D is not supplied to the gate of the driving transistor DM of the pixel circuit of the sub-panel. Here, since the data voltage written at the time of previous light-emitting of the pixel circuit is held in the capacitor Cst of the pixel circuit of the sub-panel, the driving transistor DM becomes an electrically conductive state. Since a high potential side power supply line and a low potential side power supply line are connected in common to each pixel circuit of the main panel and the sub-panel and the voltage between the high potential side power supply line and the low potential side power supply line is set to be a value which exceeds the light-emitting threshold voltage of the light-emitting element OLED, an electric current according to the data voltage held in the capacitor Cst flows in the light-emitting element of the pixel circuit of the sub-panel. Therefore, a problem arises that it is difficult to reliably make the panel (in this case, the sub-panel) of the side which should be made to not emit light be in a non-luminescent state and also power is wasted. This problem also arises similarly in a case where while the sub-panel is made to emit light, the main panel is made to not emit light.
Also, an aspect which makes the sub-panel be in a non-luminescent state by writing non-luminescence data into the pixel circuit of the sub-panel side, thereby making the capacitor Cst hold a non-luminescence voltage, can be assumed. However, in this case, the voltage of the capacitor Cst varies from the non-luminescence data voltage due to a leakage current of the switching transistor SM, so that a problem where it is difficult to reliably maintain a non-luminescent state is still not resolved.